Controlling start up in a network

ABSTRACT

A method for controlling start-up of a network is provided. The method includes receiving a message from one node of a plurality of nodes at a hub while the network is in an unsynchronized state, relaying the message to the other nodes of the plurality of nodes of the network independent of the content of the message, and blocking all messages from the one node of the plurality of nodes until a relaying condition is met.

CROSS REFERENCE To RELATED APPLICATIONS

This application is related to and claims the benefit of the filing dateof the following provisional applications:

Ser. No. 60/523,899, entitled “CONTROLLED START UP IN A TIME DIVISIONMULTIPLE ACCESS SYSTEM” filed on Nov. 19, 2003.

Ser. No. 60/523,900 entitled “COMMUNICATION FAULT CONTAINMENT VIAINDIRECT DETECTION,” filed on Nov. 19, 2003.

Ser. No. 60/523,783 entitled “PARASITIC TIME SYNCHRONIZATION FOR ACENTRALIZED TDMA BASED COMMUNICATIONS GUARDIAN” filed on Nov. 19, 2003.

Ser. No. 60/523,896 entitled “VOTING MECHANISM FOR TRANSMISSION SCHEDULEENFORCEMENT,” filed on Nov. 19, 2003.

Ser. No. 60/523,782, filed on Nov. 19, 2003 and entitled “HUB WITHINDEPENDENT TIME SYNCHRONIZATION” (the '782 Application).

Ser. No. 60/523,785, filed on Nov. 19, 2003 and entitled “PRIORITY BASEDARBITRATION FOR TDMA SCHEDULE ENFORCEMENT IN A DUAL CHANNEL SYSTEM” (the'785 Application).

Ser. No. 60/560,323, filed on Apr. 6, 2004, and entitled “MESSAGEAUTHENTICATION IN A COMMUNICATION NETWORK” (the '323 Application).

Each of these provisional applications is incorporated herein byreference.

This application is also related to the following co-pendingnon-provisional patent applications:

Attorney docket number H0004947 (400.004US01) entitled “COMMUNICATIONFAULT CONTAINMENT VIA INDIRECT DETECTION,” filed on even date herewith.

Attorney docket number H0005281 entitled “PARASITIC TIME SYNCHRONIZATIONFOR A CENTRALIZED TDMA BASED COMMUNICATIONS GUARDIAN,” filed on evendate herewith.

Attorney docket number H0005065 (400.006US01) entitled “VOTING MECHANISMFOR TRANSMISSION SCHEDULE ENFORCEMENT” filed on even date herewith.

Attorney docket no. H0005459 (400.010US01) entitled “PRIORITY BASEDARBITRATION FOR TDMA SCHEDULE ENFORCEMENT IN A MULTI-CHANNEL SYSTEM”filed on even date herewith (the '459 Application).

Attorney docket no. H0005031 (400.005US01) entitled “ASYNCHRONOUS HUB”filed on even date herewith (the '031 Application).

Attorney docket no. H0007587 (400.064US01) entitled “PORT DRIVENAUTHENTICATION IN A NETWORK” filed on even date herewith (the '587Application).

Each of these non-provisional applications is incorporated herein byreference.

BACKGROUND

Communication networks are used in a variety of applications includingtelephone and computer systems, weapons systems, navigational systems,and advanced control systems in cars, aircraft and other complexsystems. Given the variety of applications, many kinds of communicationsnetworks have been developed over the years. One common characteristicof communication networks is the use of a communication medium thatinterconnects various nodes on the network. Various topologies andprotocols have been developed to control communications between thenodes of these networks.

One type of network is referred to as Time Division Multiple Access(TDMA). In a TDMA network, nodes in the network are assigned time slotsfor communicating over the network. Many different TDMA protocols havebeen developed for communication between nodes of a network. Forexample, these protocols include TTP/C, SAFEbus, FlexRay and other TDMAprotocols.

In many time-triggered protocols, such as the TTP/C Specification, aguardian is used to monitor messages to prevent faulty messages frompropagating through the network. Left unchecked, the nodes producingfaulty transmissions can interfere with the ability of the other nodesto properly start up the network and bring it from an unsynchronizedstate to a synchronized state. The guardian often monitors messages toassure that transmission characteristics, including but not limited to,transmission rate and order, are acceptable. Through the guardian'sanalysis of the content of the frames, faulty transmissions are detectedso as to limit their influence on network start up and operation.Unfortunately, due to the complexity of the communication system andprotocol, the guardian is a complex component of the hub and typicallyrequires a significant amount of hardware, software and testing toimplement and maintain. This adds expense to the design and operation ofa network with a central guardian.

Therefore, a need exists for a simpler mechanism for reducing the impactof faulty transmissions on network start up.

SUMMARY

Embodiments of the present invention provide a simpler mechanism forreducing the impact of faulty transmissions on network start up. In oneembodiment, the hub blocks all messages by any particular node in thenetwork after forwarding a message from the node until a relayingcondition is met. For example, the relaying condition in one embodimentis entry of the network into a synchronous state. In other embodiments,the synchronization condition is messages transmitted by a selectednumber of other nodes, the lapse of a time that is sufficient for anetwork to enter a synchronous state, or any other appropriate criteriathat allows the hub to limit the influence of the node on the start-upof the network without analyzing the message at the hub.

In one embodiment, a method for controlling start-up of a network isprovided. The method includes receiving a message from one node of aplurality of nodes at a hub while the network is in an unsynchronizedstate, relaying the message to the other nodes of the plurality of nodesof the network independent of the content of the message, and blockingall messages from the one node of the plurality of nodes until arelaying condition is met.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one embodiment of a star network thatimplements a distributed, time-triggered protocol with a hub thatcontrols the influence of nodes in the network over start-up of thenetwork without analyzing the content of messages from the nodes.

FIG. 2 is a block diagram of another embodiment of a star network in anelectronic system.

FIG. 3 is a flow chart of one embodiment of a process for a hub forlimiting the influence of a node on a network in an unsynchronizedstate.

FIGS. 4, 5, and 6 are flow charts of embodiments of processes forimplementing various relaying conditions for removing a block on a nodein an unsynchronized state.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which is shown byway of illustration specific illustrative embodiments in which theinvention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention, and it is to be understood that other embodiments may beutilized and that logical, mechanical and electrical changes may be madewithout departing from the spirit and scope of the present invention.The following detailed description is, therefore, not to be taken in alimiting sense.

Embodiments of the present invention provide a network that uses asimplified guardian in a hub to reduce the impact of a faultytransmission during network start up. In one embodiment, the hub blocksall messages from a node once the node has sent one message during anunsynchronized state. In this manner, the hub is able to indirectlydetect a faulty node and limit its affect on the network by effectivelyisolating the node for a limited time. The ability to indirectly detectthe faulty node is also described in co-pending, Provisional ApplicationSer. No. 60/523,900, entitled “COMMUNICATION FAULT CONTAINMENT VIAINDIRECT DETECTION” and co-pending non-provisional patent applicationattorney docket number H0004947 (400.004US01) entitled “COMMUNICATIONFAULT CONTAINMENT VIA INDIRECT DETECTION.”

FIG. 1 is one embodiment of a network indicated generally at 100.Network 100 includes hubs 102 and 104 connected in a star configurationwith nodes 106-1 to 106-N. Hubs 102 and 104 are referred to collectivelyas “the hub” of network 100. In this embodiment, network 100 includestwo channels of communication for each node 106-1 to 106-N. Hub 102provides the first communication channel between the nodes 106-1 to106-N. Hub 104 provides the second communication channel between thenodes 106-1 to 106-N. Data is transmitted in messages, e.g., frames fromone node to another in the network 100. Each node transmits each messageto both of hubs 102 and 104. Hubs 102 and 104 then selectively transmitthe messages to the other nodes to provide 1:N communication for eachnode.

In one embodiment, the network 100 implements a distributed,time-triggered communication protocol. For example, in one embodiment,the time-triggered protocol TTP/C is used. In other embodiments, otherappropriate time division multiple access (TDMA) protocols are used innetwork 100.

In one embodiment, the nodes 106-1 to 106-N are assigned time slots touse for transmission in a synchronized state. To enter the synchronizedstate, at least one of the nodes 106-1 to 106-N sends a start-up signalin an unsynchronized state. In the TTP/C protocol this is referred to asa Cold Start Frame. The hub receives the start-up signal from one of thenodes 106-1 to 106-N and forwards it on to the other nodes of thenetwork. When N or more of the nodes 106-1 to 106-N acknowledges thestart-up signal, the network enters a synchronized state and each nodetransmits messages in its assigned time slot, where N is selected toachieve the required degree of fault tolerance, e.g., N is equal to 2for single fault tolerance.

In one embodiment, the hubs 102 and 104 recognize the synchronized statebased on reception of out-of-band signals. For example, in oneembodiment, the hubs 102 and 104 detect synchronized state when beacons,e.g., action time signals, are received from the nodes 106-1 to 106-N asdescribed in provisional application Ser. No. 60/523,783 entitled“PARASITIC TIME SYNCHRONIZATION FOR A CENTRALIZED TDMA BASEDCOMMUNICATIONS GUARDIAN” filed on Nov. 19, 2003 and non-provisionalapplication attorney docket number H0005281 entitled “PARASITIC TIMESYNCHRONIZATION FOR A CENTRALIZED TDMA BASED COMMUNICATIONS GUARDIAN,”filed on even date herewith. According to the TTP/C Standard, theseaction time signals indicate the determination of each node as to thebeginning of the next time slot. In one embodiment, entrance into thesynchronous state is determined based on guardian messages for votedschedule enforcement as described in co-pending provisional applicationSer. No. 60/523,896 entitled “VOTING MECHANISM FOR TRANSMISSION SCHEDULEENFORCEMENT,” filed on Nov. 19, 2003 and non-provisional applicationattorney docket number H0005065 (400.006US01) entitled “VOTING MECHANISMFOR TRANSMISSION SCHEDULE ENFORCEMENT” filed on even date herewith.

In operation, hubs 102 and 104 limit the influence of each of nodes106-1 to 106-N on the start up procedure of the network 100 withoutanalyzing the content of messages from the nodes. Assuming that network100 is not synchronized, one of the nodes, e.g., 106-1, sends a start-upmessage, e.g., a Cold Start Frame message, to the hubs 102 and 104. Eachhub 102 and 104 forwards the message on to the other nodes 106-2 to106-N. In one embodiment, hubs 102 and 104 implement port drivenauthentication as described in the '323 Application and the '587Application. In another embodiment, each node is limited to transmittinga start-up message on only one channel. In one embodiment, each node isassigned to a specific channel such that any given node could beassigned to any of the channels in the network.

In one embodiment, hubs 102 and 104 reduce the influence of a node onthe start-up procedure by allowing one message to be sent in theunsynchronized state and then blocking all other messages from the nodeuntil a relaying condition is met. The hubs 102 and 104 keep track ofblocks on a node-by-node basis. When the relaying condition is met, theblock on the node is removed.

In one embodiment, the hubs 102 and 104 apply one or more relayingconditions to determine when to remove a block on a selected node thathas been blocked due to transmitting a message in the unsynchronizedstate. First, in one embodiment, one relaying condition is based on thepassage of enough time such that network synchronization should beachieved. The time is long enough for the message to be recognized andsynchronous operation to commence. Further, the time should be longerthan it takes for good nodes, having observed the transmission to backoff, and one to send another subsequent start-up message, e.g., enoughtime for a failed start-up attempt to be recognized and a subsequentstart up attempt initiated by another node to commence. With this, thetime delay ensures that another node will have enough time to back offand recover from any erroneous behavior caused by the original sourcednode, such that another node will source a good message and so start thenetwork.

One embodiment of this relaying condition is shown and described withrespect to FIG. 4. Further, in one embodiment, another relayingcondition is based on transmissions by a selected number of other nodesin the unsynchronized state. With this condition, a block on a node isremoved once the appropriate number of other nodes has transmitted. Oneembodiment of this relaying condition is described below with respect toFIG. 5. In another embodiment, another relaying condition is met whenthe network moves to the synchronized state such as shown and describedwith respect to FIG. 6. Other relaying conditions can be used thatappropriately limit the influence of one node on the start-up procedure.

In other embodiments, only a single hub and single communication channelare provided. This is represented in FIG. 1 with the removal of one ofthe two hubs 102 or 104 and its connections to the nodes 106-1 to 106-N.

FIG. 2 is a block diagram of a system indicated at 200 that uses acommunication network 100 of the type describe above with respect toFIG. 1. FIG. 2 further shows that the nodes 106-1 to 106-N are connectedto a number of electronic devices 208-1 to 208-N, e.g., sensors,processors, actuators, controllers, input devices and the like thatcommunicate date in frames over the network 100.

FIG. 3 is a flow chart of one embodiment of a process for a hub forlimiting the influence of a node on a network in an unsynchronizedstate. The process begins at block 300 in a start-up enforcementparadigm. In this paradigm, the hub limits the influence of a node onstart-up by controlling whether messages from a node are forwarded toother nodes or are blocked at the hub. In essence, the hub selectivelyblocks transmissions from a node, e.g., by not relaying messages, tolimit its influence on the start-up process while in the unsynchronizedstate. When the network enters a synchronized state, the hub uses aconventional synchronous enforcement paradigm, with the guardianenforcing slot order or the guardian performing a fault tolerantarbitration schemes as detailed in the '782 Application, the '031Application, the '785 Application, and the '459 Application.

At block 302, the process detects the start of a message from a node,e.g., by detecting a start-of-frame signal or flag. In otherembodiments, any other activity on the channel is used to detect anattempt to transmit. At block 304, the process determines whether thenode that is beginning to transmit is currently blocked. If the node iscurrently blocked, the process does not relay the message at block 306.If however, the node is not currently blocked, the process startsrelaying the message at block 308. At block 310, the process instigatesa block for all further messages from the node. This block is left inplace for the node until a relaying condition is met such as determinedby the processes described below in FIGS. 4, 5, and 6. It is noted thatany one or more of the processes shown in FIGS. 4, 5 and 6 can run inparallel.

FIG. 4 is a flow chart of one embodiment of a process for removing ablock on a node based on the time after a block is applied to the nodeat the hub. The process begins at block 402 when the block is applied tothe node at the hub. At block 404, the process starts a timer. The timeris set to a value that allows the hub to determine if a sufficientperiod of time has elapsed such that entry into the synchronous statewould normally have occurred. The value of this timer is long enough forthe message to be recognized and synchronous operation to commence.Further, the time should be longer than it takes for good nodes, havingobserved the transmission to back off, and one to send anothersubsequent start-up message, e.g., enough time for a failed start-upattempt to be recognized and a subsequent start up attempt initiated byanother node to commence. With this, the time delay ensures that anothernode will have enough time to back off and recover from any erroneousbehavior caused by the original sourced node, such that another nodewill source a good message and so start the network. At block 406, theprocess determines whether the timer has expired. If so, the hub removesthe block for the node at block 408. If sufficient time has not passed,then the hub retains the block on the node and returns to block 406 todetermine whether the timer has expired.

FIG. 5 is a flow chart of one embodiment of a process for removing ablock on a node based on the number of nodes that have transmitted inthe unsynchronized state. In one embodiment, the hubs track the numberof transmissions from each node during the unsynchronized state. In oneembodiment, the hub blocks messages from a node until messages from anumber of nodes equal to the number of channels in the network have beentransmitted.

The process begins at block 502 when the block is applied to the node.At block 504, the process determines whether another node hastransmitted since the last message from the node. If a node has nottransmitted, the process returns to block 504. If, however, another nodehas transmitted, the process proceeds to block 506. At block 506, theprocess determines whether the number of nodes that has transmitted isgreater than or equal to N. In one embodiment, the number N is equal tothe number of channels in the network. In another embodiment, the numberN is equal to the number of channels that a node is allowed to attemptstart-up of the network. If the process determines that the appropriatenumber of nodes has transmitted, then the block is removed at block 508and the node is allowed to transmit.

FIG. 6 is a flow chart of one embodiment of a process for removing ablock on a node based on entry into the synchronous state. At block 602,the process receives an out-of-band signal that indicates thesynchronization state of the network. In one embodiment, the out-of-bandsignals are beacons, e.g., action time signals, as described inprovisional application Ser. No. 60/523,783 entitled “PARASITIC TIMESYNCHRONIZATION FOR A CENTRALIZED TDMA BASED COMMUNICATIONS GUARDIAN”filed on Nov. 19, 2003 and non-provisional application attorney docketnumber H0005281 entitled “PARASITIC TIME SYNCHRONIZATION FOR ACENTRALIZED TDMA BASED COMMUNICATIONS GUARDIAN,” filed on even dateherewith. According to the TTP/C Standard, these action time signalsindicate the determination of each node as to the beginning of the nexttime slot. In one embodiment, the out-of-band signals are guardianmessages for voted schedule enforcement as described in co-pendingprovisional application Ser. No. 60/523,896 entitled “VOTING MECHANISMFOR TRANSMISSION SCHEDULE ENFORCEMENT,” filed on Nov. 19, 2003 andnon-provisional application attorney docket number H0005065(400.006US01) entitled “VOTING MECHANISM FOR TRANSMISSION SCHEDULEENFORCEMENT” filed on even date herewith. In other embodiments, anyappropriate out-of-band signal is used that indicates the state of thenetwork as synchronous or non-synchronous.

The process determines, at block 604, whether the network is in asynchronized state based on the out-of-band signal. The state ofsynchronization determines whether the hub exits the start-upenforcement paradigm and enters the synchronous enforcement paradigm. Atblock 606, the process continues start-up enforcement when theout-of-band signals indicate that the network is in an unsynchronizedstate. At block 608, the process removes any blocks and enters thesynchronous enforcement at block 610 when the out-of-band signalindicates that the network is in a synchronous state.

The methods and techniques described here may be implemented in digitalelectronic circuitry, or with a programmable processor (for example, aspecial-purpose processor or a general-purpose processor such as acomputer) firmware, software, or in combinations of them. Apparatusembodying these techniques may include appropriate input and outputdevices, a programmable processor, and a storage medium tangiblyembodying program instructions for execution by the programmableprocessor. A process embodying these techniques may be performed by aprogrammable processor executing a program of instructions on a machinereadable medium to perform desired functions by operating on input dataand generating appropriate output. The techniques may advantageously beimplemented in one or more programs that are executable on aprogrammable system including at least one programmable processorcoupled to receive data and instructions from, and to transmit data andinstructions to, a data storage system, at least one input device, andat least one output device. Generally, a processor will receiveinstructions and data from a read-only memory and/or a random accessmemory. Storage devices or machine readable medium suitable for tangiblyembodying computer program instructions and data include all forms ofnon-volatile memory, including by way of example semiconductor memorydevices, such as EPROM, EEPROM, and flash memory devices; magnetic diskssuch as internal hard disks and removable disks; magneto-optical disks;and DVD disks. Any of the foregoing may be supplemented by, orincorporated in, specially-designed application-specific integratedcircuits (ASICs).

A number of embodiments of the invention defined by the following claimshave been described. Nevertheless, it will be understood that variousmodifications to the described embodiments may be made without departingfrom the spirit and scope of the claimed invention. Accordingly, otherembodiments are within the scope of the following claims.

1. A method for controlling start-up of a network, the methodcomprising: receiving a message from one node of a plurality of nodes ata hub while the network is in an unsynchronized state; relaying themessage to the other nodes of the plurality of nodes without analyzingthe content of the message; and when the network remains in anunsynchronized state, blocking all messages from the one node of theplurality of nodes until a synchronous state is detected, a selectnumber of nodes of the plurality of nodes has transmitted a message, ora period of time has lapsed that is sufficient to allow the network tostart-up.
 2. The method of claim 1, and further including detecting thestate of synchronization of the network based on out-of-band signaling.3. The method of claim 1, and further including monitoring signalsreceived at the hub to detect entry into the synchronous state.
 4. Themethod of claim 3, wherein monitoring signals comprises monitoring forat least one of beacons from the plurality of nodes or guardian messagesfor voted schedule enforcement.
 5. The method of claim 3, whereinblocking all messages comprises not relaying the message independent ofthe content of the message.
 6. A method for controlling start-up of anetwork, the method comprising: receiving a message from one node of aplurality of nodes at a hub while the network is in an unsynchronizedstate; relaying the message to the other nodes of the plurality of nodesof the network independent of the content of the message; and blockingmessages from the one node at the hub from being forwarded to othernodes of the plurality of nodes until the network is synchronized or aselect number of other ones of the plurality of nodes have transmitted amessage in the unsynchronized state.
 7. The method of claim 6, whereinblocking messages comprises failing to relay messages to other nodes inthe network independent of the content of the message.
 8. A method forcontrolling start-up of a network, the method comprising: receiving amessage from one node of a plurality of nodes at a hub while the networkis in an unsynchronized state; relaying the message to the other nodesof the plurality of nodes of the network independent of the content ofthe message; and blocking all messages from the one node of theplurality of nodes until a relaying condition is met.
 9. The method ofclaim 8, wherein blocking all messages comprises blocking all messagesfrom the one node until the network enters a synchronous state, or aselect number of other nodes of the plurality of nodes transmits amessage, or a period of time lapses that is sufficient to allow thenetwork to start-up.
 10. A network, comprising: at least one hub; aplurality of nodes coupled to the at least one hub in a starconfiguration; wherein the at least one hub and the plurality of nodescommunicate using a time-triggered protocol; and wherein the hub allowseach node to transmit one message on the network in an unsynchronizedstate before the hub blocks messages on the network from that node. 11.The network of claim 10, wherein the hub blocks all messages from thenode in the unsynchronized state until at least one other node hastransmitted a message in the unsynchronized state.
 12. The network ofclaim 10, wherein the hub blocks all messages in an unsynchronized stateuntil a number of nodes of the plurality of nodes equal to the number ofchannels in the network has transmitted a message in the unsynchronizedstate.
 13. A machine-readable medium having instructions stored thereonfor a method for controlling start-up of a network, the methodcomprising: receiving a message from one node of a plurality of nodes ata hub while the network is in an unsynchronized state; relaying themessage to the other nodes of the plurality of nodes without analyzingthe content of the message; monitoring the state of synchronization ofthe network; and when the network remains in an unsynchronized state,blocking all messages from the one node of the plurality of nodes untila synchronous state is detected.
 14. The machine-readable medium ofclaim 13, and further comprising ceasing to block messages from a nodeonce a select number of other nodes of the plurality of nodes hastransmitted a message.
 15. The machine-readable medium of claim 13, andfurther comprising ceasing to block messages after a period of time haslapsed that is sufficient to allow the network to start-up.
 16. Themachine-readable medium of claim 13, wherein monitoring the state ofsynchronization comprises monitoring an out-of-band signal.
 17. Themachine-readable medium of claim 13, wherein monitoring the state ofsynchronization comprises monitoring beacon signals sent from theplurality of nodes to the hub.
 18. The machine-readable medium of claim13, wherein monitoring the state of synchronization comprises monitoringa guardian message used for voted schedule enforcement.
 19. Amachine-readable medium having instructions stored thereon for a methodfor controlling start-up of a network, the method comprising: receivinga message from one node of a plurality of nodes at a hub while thenetwork is in an unsynchronized state; relaying the message to the othernodes of the plurality of nodes of the network independent of thecontent of the message; and blocking all messages from the one node ofthe plurality of nodes until a relaying condition is met.
 20. Themachine-readable medium of claim 19, wherein blocking all messagescomprises blocking all messages from the one node until the networkenters a synchronous state, or select number of other node of theplurality of nodes transmits a message, or a period of time lapses thatis sufficient to allow the network to start-up.
 21. A method forcontrolling start-up of a network, the method comprising: receiving amessage from one node of a plurality of nodes at a hub while the networkis in an unsynchronized state; relaying the message to the other nodesof the plurality of nodes without analyzing the content of the message;and when the network remains in an unsynchronized state, blocking allmessages from the one node of the plurality of nodes until a selectnumber of nodes of the plurality of nodes has transmitted a message. 22.The method of claim 21, wherein blocking all messages from the one nodeof the plurality of nodes until a select number of nodes of theplurality of nodes has transmitted a message comprises blocking allmessages from the one node of the plurality of nodes until a number ofnodes of the plurality of nodes equal to the number of channels havetransmitted in the unsynchronized state.
 23. The method of claim 21,wherein blocking all messages comprises not relaying the messageindependent of the content of the message.
 24. The method of claim 21,wherein blocking all messages from the one node of the plurality ofnodes until a select number of nodes of the plurality of nodes hastransmitted a message comprises blocking all messages from the one nodeof the plurality of nodes until a number of nodes of the plurality ofnodes equal to the number of channels a node is authorized to transmiton have transmitted in the unsynchronized state.
 25. The method of claim21, and further comprising unblocking the one node when the selectnumber of nodes has transmitted in the unsynchronized state.
 26. Amethod for controlling start-up of a network, the method comprising:receiving a message from one node of a plurality of nodes at a hub whilethe network is in an unsynchronized state; relaying the message to theother nodes of the plurality of nodes without analyzing the content ofthe message; and when the network remains in an unsynchronized state,blocking all messages from the one node of the plurality of nodes untila period of time has lapsed that is sufficient to allow the network tostart-up.
 27. The method of claim 26, wherein blocking all messagesincludes setting a timer on a per node basis when a block is applied tothe node.
 28. The method of claim 27, and firther comprising unblockingthe node when the timer associated with the node expires.
 29. Anapparatus for controlling start-up in a network, the apparatuscomprising: means for relaying messages from one node to other nodes ofa plurality of nodes; means, coupled to the means for relaying, forblocking messages from the one node after relaying one message from theone node in an unsynchronized state; and means, coupled to the means forrelaying, for removing the block when a relaying condition is met. 30.The apparatus of claim 29, wherein the means for removing the blockcomprises means for removing a block when a synchronous state isdetected, a select number of nodes of the plurality of nodes hastransmitted a message, or a period of time has lapsed that is sufficientto allow the network to start-up.